The present invention relates to an air permeable grate or screen for selectively precluding passage of items, such as birds and rodents through a duct, and more particularly to a vent hood assembly having a pivotally mounted vent screen.
Ductwork from clothes dryers, bathroom exhaust ductwork, and the like which vent to an outdoor environment are typically provided with hooded vents that have some type of flap, which opens under air pressure from exhaust fans. Unfortunately, these flaps are often lifted open by birds and other small animals looking for nesting areas. Nesting materials can clog the vent hood causing disfunction, and, in an extreme case, lint buildup which can create a fire hazard to a dryer""s heating element. In addition, animal droppings can soil the hood interior leading to unwanted odors which can be difficult to trace. Furthermore, once an animal is inside exhaust ductwork, the animal may peck or bite holes in the ductwork which can lead to further disfunction. Holes which became large enough for the animal to squeeze through provide entrances for the animal into the buildings walls or interior spaces.
The prior art has shown some attempts at solving the above-described problems. U.S. Pat. No. 5,616,076 to Higgins discloses a guard with vent bars for attachment to the mouth of a vent hood. Higgins discloses either completely attaching the guard to the mouth of the vent and selling the hood as a solid unit or attaching the guard by using a mounting strap and hinged base which are attached somehow to the hood using 3.18 mm holes provided in the base and strap. While this guard may be effective at preventing animal entry, it is either impossible or inconvenient to remove the guard for cleaning purposes. U.S. Pat. No. 5,547,422 to Seboldt discloses a protector having a cage-like body member connectable to a wall surrounding a duct outlet. The body member has a bottom panel which is provided with hinge means to permit the panel to be movable to an open condition. Again, while the protector may effectively prevent animal entry, one would not be encouraged to clean the device frequently as it would require awkward arm maneuvers to reach between the building wall and pivoted panel. Repeated opening and closing of the bendable metal cloth of the cage-like member will eventually irreparably distort the device. In addition, one may not even want to install such a protector as it would require placing additional holes in the building exterior. Furthermore, many building owners would find such a cage-like member an unnattractive addition to the building. U.S. Pat. No. 5,046,408 to Eugenio discloses a screen placed onto the opening of a hood which is fastened by xe2x80x9cunique clips.xe2x80x9d Again, entry into the hood is either impossible or inconvenient.
Thus, there is a need for a vent screen which can prevent animals from entering into a hood assembly and creating havoc in the duct work. There is further a need for such a vent screen which can be easily assembled onto a hood without the need of screws. There is further a need for a vent screen which is sturdy enough to withstand repetitive opening and closing operations. There is further a need for a vent screen which can be easily removed for cleaning and which, when in an open position, does not get in the way of the cleaning process. There is further a need for a vent screen having bars that limit the amount of cleaning necessary.
Thus, it is an object of the present invention to provide a vent screen which will protect the interior of hoods and duct work from birds and other animals.
It is another object of the present invention to provide a vent screen which can be attached to a hood assembly using a snap-fit connection.
It is another object of the present invention to provide a vent screen which is pivotal with respect to the hood assembly and which pivots in a direction to move the area of the screen requiring cleaning in a direction facing the user and in a direction which does not hinder entry into the hood assembly for cleaning.
It is a further object of the present invention to provide a vent screen which can be snapped closed from its pivoted open position.
It is a further object of the present invention to provide a vent screen having vent bars with a tapered leading edge for ease in cleaning.
It is yet another object of the present invention to provide a vent screen which is molded to provide the pivot bars and for molding an aerodynamic shape in the vent bars.
It is a further object of the present invention to provide a hood assembly with retention tabs for retaining the vent screen in a closed position and pivot recesses for allowing the vent screen to pivot to an open position.
Other objects will in part be obvious and in part appear hereinafter.
In a preferred embodiment of the present invention, the hood assembly for exterior ducts comprises a hood for connecting to a terminal end of a duct for directing air flow from along an axis of the duct to an off-axis direction, preferably substantially perpendicularly, the hood defining an opening for permitting fluid flow in the off-axis direction, and a screen releasably connected to the hood to substantially occupy the entire opening, the screen having a plurality of vent bars extending across the hood opening, the vent bars including a leading edge with respect to air flow passing through the opening, wherein the screen is pivotally mounted to the hood.
The hood may comprise a mounting panel for surrounding the terminal end of a duct such that the screen is pivotally mounted to the hood adjacent the mounting panel. This assists the user in cleaning the hood and screen by allowing the screen to be pivoted towards a building wall in an out of the way position. The pivotal nature of the screen with respect to the hood may be accomplished by pivot bars extending from a pivoting end of the screen received within recesses in the hood.
Preferably, a cross-section of the leading edge of the vent bars is tapered to a point. The cross-section may be triangular, or may be defined by the intersection of two circles. The tapered leading edge reduces the stagnation points of air flow past the vent screen, thus reducing the debris that is collected on the leading surface. The hood and screen are preferably both molded in plastic.
The hood assembly further may comprise cooperating friction fit mechanisms on the hood and screen or tabs on the hood for releasably engaging the screen to the hood to preclude rotation. Stopping blocks within the hood prevent over-rotation of the screen into the hood.
Thus, a preferred embodiment of the present invention embraces a method for protecting an opening of a duct hood, the duct hood having a mounting panel accessible to a vent duct, the method comprising the steps of providing the duct hood with a pair of recesses on an inner side of the hood adjacent the mounting panel, providing the duct hood with tabs on an outer side of the hood, opposite the recesses, attaching the mounting panel to a building wall over a vent duct, providing a vent screen with crossing vent bars creating apertures sized to prevent the ingress of small animals, providing the vent screen with pivot bars on opposite sides of a pivoting end of the vent screen, the pivot bars substantially sharing a plane with the vent screen, inserting the pivot bars into the recesses of the duct hood, pivoting the vent screen to cover the opening, and pushing the vent screen past the tabs of the duct hood to frictionally retain the vent screen in a closed position substantially flush with the opening of the duct hood.
The cleaning of the duct hood and the inner surface of the vent screen may be accomplished by pulling the closing end of the vent screen away from the opening to pull the screen past the tabs of the duct hood, pivoting the vent screen about the recesses in the duct hood and towards the building wall to place the vent screen in an open position, removing lint and debris from the duct hood and cleaning an inner surface of the vent screen, pivoting the vent screen back to the closed position, and pushing the screen past the tabs of the duct hood.
The foregoing and other features and advantages of the invention will be more readily understood and fully appreciated from the following detailed description, taken in conjunction with the accompanying drawings.